The package keeps track of whether a command defined in a document preamble is actually used somewhere in the document. After the package is loaded in the preamble of a document, all \newcommand (and similar command definitions) between that point and the beginning of the document will be marked for logging. At the end of the document a report of command usage will be printed in the TeX log, for example:
– “mdash was used on line 25”;
– “ndash was never used”.

The author is Michael J. Downes. The package is Copyright © 1999 Michael John Downes, © 2012 TeX Users Group.